The invention relates generally to apparatus and systems for suppressing sounds resultant from snoring and more particularly to systems for suppressing sounds produced by snoring wherein the originating snoring sounds are substantially suppressed by generating sound canceling signals.
Many attempts have been made to overcome the problem of snoring for both the snoring person and other persons that may hear the snoring sounds. Many systems and methods for eliminating the problem of snoring are designed to awaken or otherwise interrupt the person generating the snoring sounds. For example, some systems activate an alarm based on a predetermined loudness level of the snore sensed by a sound sensor. Another system includes an eye cover which has an actuating mechanism for activating a flashing light so that the snorer is awakened upon sensing of snoring sounds. However, such systems unnecessarily wake up a snoring person so that the snoring person is deprived of a comfortable rest.
Other systems which have been developed in an attempt to overcome the problem of snoring include air bags which may be mounted to the back of the snoring person to prevent the person from lying on their back. This may prevent snoring, but may do so at the expense of comfort. Another system includes a sling which is worn over the mouth of a person to keep the mouth closed so that the wearer is unable to generate a snoring sound. These systems unnecessarily restrict the physical comfort of the snoring individual so that the snoring individual is forced to sleep in an unnatural state.
Other systems, such as ear plugs for the non-snoring person reduce the effects of snoring by attempting to completely block all sounds (particularly the snoring sound signal) from reaching an ear drum of the non-snoring person. This allows the snoring person to sleep comfortably and continue snoring. However, such systems are typically onerous and possibly life threatening to the non-snoring person since the non-snoring person might be unable to hear other audible signals, such as audible smoke alarm or fire alarm warning signals.
No snoring attenuation systems are known that substantially cancel or otherwise attenuate snoring sound signals so that neither the snoring person nor another non-snoring person needs to wear an overly restrictive or unnecessarily uncomfortable snore prevention system. Although the theory of sound cancellation through the use of canceling signals is generally known, no snoring sound signal attenuation systems are known that use audible canceling signals to suppress snoring sounds. In general, audible canceling signals typically have a same amplitude but a phase angle that is 180 degrees from that of a source sound signal.
Known adaptive sound cancellation systems, cancel sounds (noise) at a location other than the source of the sound, such as at an opening in a duct. Typically, the point at which a cancellation signal is directed (cancellation point) is fixed and down stream from the signal source. For example, many systems cancel sound at a point downstream from the source of a sound such as an opening in a duct so that the control system has adequate time to determine a proper cancel signal. Therefore, where the noise cancellation point is sufficiently distant from the source of the noise, and a sensor is placed at the source and another sensor at the cancellation point, the control system may readily calculate and output a canceling signal downstream from the source.
One example is disclosed in European Patent Application 465,174 entitled "Adaptive Active Noise Cancellation Apparatus". Such a system uses a control system to cancel noise at an opening of a duct. The control system uses an adaptive filter for aiding in reducing unwanted noise in ducts. However, such known noise cancellation systems typically require the use of a plurality of microphones for determining an error signal, and a duct for conducting sound (audible) signals so that the sound source signal is directionally limited to better facilitate cancellation.
Such systems, typically determine the error signal by placing a microphone at the opening of the duct to determine the level of noise emanating from the opening of the duct. Such an error signal may then be input into an adaptive filter after being delayed by a predetermined time. A second microphone or sensor is typically placed at the source of the noise to determine the actual source sound signal. The adaptive filter uses the error signal to determine a canceling signal, having the same amplitude but a 180 degree phase difference from the error signal emanating at the opening of the duct. The output signal is typically output by a signal processor through a speaker directed at the duct opening to substantially cancel the sound signal at the opening.
However, such systems are typically limited to reducing noise signals at a single stationary point (duct opening) away from the source. Canceling signals away from the source gives these types of systems ample time to generate and evaluate error signals to better calculate canceling signals. In addition, such duct-type systems are typically not adapted to operate in an open area, such as a bed room or other room in a house. Such open areas may allow the source signal to radiate and propagate in many directions unlike the duct arrangement which guides the signals to an opening. Furthermore, such duct systems require at least two sensors, one for sensing the source sound signal and one for sensing the signal at the duct opening to determine an error signal. Also, since the duct opening is typically the only point at which noise may be radiated, the control system attempts to calculate and output a canceling signal so that the canceling signal plane of the duct opening is 180 degrees out of phase with respect to the noise signal at the plane of the duct opening.
Another known noise attenuation system, such as that disclosed in U.S. Pat. No. 4,677,676 entitled "Active Attenuation System With On-line Modeling of Speaker, Air Path and Feedback Path", also utilizes a duct arrangement. Again, such systems do not cancel at the source of the sound signal and use an additional microphone located down stream from where the canceling signal is output, to determine an error signal.
Based on the foregoing, known noise canceling systems typically cancel at a fixed, nonmoving point, such as an opening in a duct. Therefore, known noise canceling systems are typically not suitable wherein the sound to be canceled is a moving sound source such as a snoring sound source.
A problem also arises with such systems where a source may emanate in a substantially omnidirectional pattern. Such is the case with a snoring individual since snoring sounds are typically emanated in almost an omnidirectional pattern in an open room. Furthermore, it would be desirable to substantially globally cancel snoring sounds instead of attempting to locally cancel a sound at a selected point away from the source since the snoring sound may be heard at points other than one fixed point. Global reduction of the snoring sound would also be advantageous since an individual (the ears of the individual), such as a non-snoring spouse, may move throughout the night.